Mechanism for inserting and removing electronic circuit unit

ABSTRACT

In a mechanism for inserting and removing electronic circuit units against a shelf of an electrical device where the electronic circuit units are installed, the shelf includes a groove forming part, the electrical circuit unit includes a rotatable lever, a rotatable stopper, and a housing member, and the electrical circuit unit is locked with the shelf by rotating the lever.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention generally relates to mechanisms forinserting and removing electronic circuit units, and more particularly,to a mechanism for inserting and removing electronic circuit units foran electronic device, such as a communication device, an informationprocessing apparatus, and a measurement apparatus, having a shelf wherea large number of the electronic circuit units are installed.

[0003] 2. Description of the Related Art

[0004] An electronic circuit unit is installed in a shelf of anelectronic device, such as a communication device, an informationprocessing apparatus, and a measurement apparatus. A lever for insertingand removing is rotatably attached to the electronic circuit unit. Theelectronic circuit unit is connected to a connector on the back board ofthe shelf by rotating the lever. The electronic circuit unit is lockedwith the shelf in order to connect the electronic circuit unit to theconnector securely, so that a connection for electric signals isaccomplished.

[0005]FIG. 1 is a view for explaining a conventional mechanism forinserting and removing electronic circuit units. FIG. 2 is an explodedperspective view of a lever 12 for inserting and removing.

[0006] Referring to FIGS. 1 and 2, electronic circuit units 10 aremounted on a shelf 20 having a box configuration. The electronic circuitunit 10 includes the levers 12 for inserting and removing, stoppers 13,and receiving parts 14. The levers 12 for inserting and removing arerotatably attached to upper and lower parts of the front end part of anelectronic circuit board 11. The stopper 13 is attached to the lever 12for inserting and removing so as to be rotated by a spring 19 shown inFIG. 2, wherein a pin 16 is the center of the rotation of the stopper13. The stopper 13 is received by the receiving part 14. The mechanismfor inserting and removing the electronic circuit unit 10 consists ofthe lever 12 for inserting and removing, the stopper 13, and thereceiving part 14.

[0007]FIG. 3 is a view for explaining an insertion of the electroniccircuit unit 10 shown in FIG. 1 to the shelf 20 and a lock operation.Since the mechanism for inserting and removing provided at an upper partof the front end part of the electronic circuit unit 10 actssubstantially the same as the mechanism for inserting and removingprovided at a lower part of the front end part of the electronic circuitunit 10, only the mechanism for inserting and removing provided at thelower part of the front end part of the electronic circuit unit 10 willbe described and explanation of the mechanism for inserting and removingprovided at the upper part of the front end part of the electroniccircuit unit 10 will be omitted.

[0008] In a state shown in FIG. 3-(A), first the electronic circuit unit10 shown in FIG. 1 is inserted to the shelf 20, and then the lever 12for inserting and removing is rotated counterclockwise. A claw part 15comes in contact with a frame 21 of the shelf 20. The lever 12 isrotated counterclockwise based on the leverage. And thereby, the stopper13 comes in contact with the receiving part 14.

[0009] In a state shown in FIG. 3-(B), the lever 12 for inserting andremoving is further rotated counterclockwise. The stopper 13 is rotatedclockwise in a state where the pin 16 is the center of the rotation ofthe stopper 13, so that the stopper 13 is situated at an upper part ofthe receiving part 14.

[0010] In a state shown in FIG. 3-(C), the lever 12 for inserting andremoving is further rotated counterclockwise, so that the electroniccircuit unit 10 shown in FIG. 1 is further inserted to the shelf 20. Thestopper 13 is situated on a concave part 17 of the receiving part 14,and thereby the stopper 13 is locked with the receiving part 14. In thiscase, a gap having a distance y between the right end of the frame 21and the front end of the electronic circuit board 11 is made.

[0011] A surface board is provided to the electronic circuit unit 10. Ashield gasket is provided around the surface board so as to shieldagainst the leakage of an electromagnetic wave to the outside.

[0012] Meanwhile, recently, technology has progressed so that signalsconnected by the connector have a high frequency. Because of this, thelength of a contact pin at the connection part of the connector hasbecome short. Hence, it is required to make a secure connection betweenthe connector of the electronic circuit unit and the connector of theback board.

[0013] However, the conventional mechanism for inserting and removingelectronic circuit unit 10 has problems with regard to the connection ofthe connector.

[0014] First of all, the conventional mechanism for inserting andremoving electronic circuit unit 10 has a backlash, namely play withrespect to the lock by the lever 12 for inserting and removing. Hence,it is difficult to assure the connection of the connector securely.

[0015] That is, in a state shown in FIG. 3-(C), the stopper 13 isrotated clockwise wherein a pin 16 is the center of the rotation of thestopper 13, so that the stopper 13 is moved on the concave part 17 ofthe receiving part 14. And thereby, a gap having a distance X between aright end of the concave part 17 and the stopper 13 is made.Accordingly, in a state shown in FIG. 3-(C), if a force for pulling theelectronic circuit unit 10 from the shelf 20 due to a vibration, forexample, is applied to the electronic circuit unit 10, that is, if aforce is applied to the electronic circuit unit 10 in an oppositedirection to the insertion direction of the electronic circuit unit 10to the shelf 20 (in a right side direction in FIG. 3-(C)), a state shownin FIG. 3-(D) occurs. That is, the gap having the distance X between thestopper 13 and the concave part 17 of the receiving part 14 is closedand the gap between the right end of the frame 21 and the front end ofthe electronic circuit board 11 is increased from the distance y to adistance y+z.

[0016] That means, even if the electronic circuit unit 10 shown in FIG.1 is inserted to the shelf 20 and the stopper 13 is situated on theconcave part 17 of the receiving part 14 so that the stopper 13 islocked with the receiving part 14 as shown in FIG. 3-(C), backlash,namely play having a distance Z with respect to the lock by the lever 12occurs in the conventional mechanisms for inserting and removing theelectronic circuit unit 10. Hence, it is difficult to assure theconnection of the connector securely in the conventional mechanisms forinserting and removing the electronic circuit unit 10.

[0017] Second, a shield gasket is provided around the surface board ofthe electronic circuit unit 10 in the vicinity of the lever 12 forinserting and removing, so as to shield leakage of the electromagneticwave from the electronic circuit unit to the outside. In a case where anattempt is being made to connect the electronic circuit unit 10 to theshelf 20 by the lever 12 for inserting and removing, the electroniccircuit unit 10 is at first manually pushed to be inserted. And then,the lever 12 for inserting and removing is rotated counterclockwise toconnect the electronic circuit unit 10 to the shelf 20, as the operatorfeels a resistant force (an elastic force) against the insertion of theelectronic circuit unit 10, which is caused by the contact to the shieldgaskets of neighboring electronic circuit units.

[0018] However, the timing when the operator feels the resistant force(the elastic force) does not always coincide with the timing when thelever 12 for inserting and removing should be rotated to connect theelectronic circuit unit 10 to the shelf 20. Hence, the lever 12 forinserting and removing is rotated in error before the electronic circuitunit 10 is positioned to start being connected to the shelf 20. That is,it is difficult for the operator to determine to start connecting theelectronic circuit unit 10 to the shelf 20 by rotating the lever 12 forinserting and removing, due to the resistant force (the elastic force)of the shield gasket. Because of this, it is not possible to securelyconnect the electronic circuit unit 10 to the shelf 20 by rotating thelever 12 for inserting and removing.

SUMMARY OF THE INVENTION

[0019] Accordingly, it is a general object of the present invention toprovide a novel and useful mechanism for inserting and removing anelectronic circuit unit, in which one or more of the problems describedabove are eliminated.

[0020] Another and more specific object of the present invention is toprovide a mechanism for inserting and removing electronic circuit unitswherein connectors of the electronic circuit units are connected toconnectors of the back boards securely.

[0021] The above objects of the present invention are achieved by amechanism for inserting and removing electronic circuit units against ashelf of an electrical device where the electronic circuit units areinstalled, wherein the shelf includes a groove forming part, theelectrical circuit unit includes a rotatable lever having a head endwhere a fixing part is provided; a rotatable stopper connected to thelever and having a head end where an engaging part is provided; and ahousing member housing the lever and the stopper where an engagingsurface engaging with the engaging part of the stopper is providedinside thereof, the electrical circuit unit is locked with the shelf byrotating the lever so as to engage the groove forming part of the shelfwith the engaging part of the stopper, and the engagement between theengaging surface of the housing member and the engaging part of thestopper is not off even if a force to lift the lock is applied to theelectrical circuit unit.

[0022] According to the above mentioned invention, the fixing part ofthe lever is fixed to the groove forming part of the shelf by rotatingthe lever so that the electrical circuit unit is locked with the shelf.Even if the force to lift the lock is applied to the electrical circuitunit, the engagement between the engaging surface of the housing memberand the engaging part of the stopper is not off (not terminated). Hence,it is possible to accomplish locking by the lever not having play andthereby securely connect with a connector having even a short connectionlength.

[0023] The housing member may further include a rotation stopping part,and the lever cannot be moved, after the lever is further rotated sothat the lever comes in contact with the rotation stopping part.

[0024] According to the above mentioned invention, when the lever comesin contact with the rotation stopping part, the lever cannot be furtherrotated. Therefore, further leverage applied to the lever cannot work soas to prevent damages based on the connection between the connector ofthe electronic circuit unit and the connector of the back board wiringboard of the shelf.

[0025] The housing member may further include an engaging lifting guidesurface, and the engaging part of the stopper may be guided on theengaging lifting guide surface by rotating the stopper and then thelever may be rotated, so that the lock between the electrical circuitunit and the shelf is off.

[0026] According to the above mentioned invention, it is possible torotate the stopper with a light force. Hence, it is possible to lift thelock between the electrical circuit unit and the shelf by a simpleoperation.

[0027] The above object of the present invention is achieved by amechanism for inserting and removing electronic circuit units against ashelf of an electrical device where the electronic circuit units areinstalled, wherein the shelf includes a groove forming part, theelectrical circuit unit includes a rotatable lever having a head endwhere a fixing part is provided; a rotatable stopper connected to thelever and having a head end where an engaging part is provided; and ahousing member housing the lever and the stopper where a projection partfixing an insertion guide surface where the engaging part is guided tothe stopper by rotating the lever is provided inside thereof, and if adesignated force is applied to the lever, the lever is rotated and thefixing part of the lever is engaged with the groove forming part of theshelf, and fixing of the stopper by the projection part of the housingmember is lifted so that the engaging part of the stopper comes incontact with the insertion guide surface.

[0028] According to the above mentioned invention, fixing of the stopperis lifted. And thereby, the stopper slides on the projection part, theengaging part of the stopper moves in a direction of the insertion guidesurface, and the lever is rotated. Therefore, the operator can easilydetermine visually when lock operation by rotating the lever with hisfinger can be started.

[0029] The stopper may further include another groove forming part, andthe stopper may be fixed to the projection part by engaging the othergroove forming part with the projection part of the housing member.

[0030] According to the above mentioned invention, it is possible toengage the groove forming part of the stopper with the projection partof the housing member securely, so that the stopper can be fixedsecurely.

[0031] Other objects, features, and advantages of the present inventionwill become more apparent from the following detailed description whenread in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is a view for explaining a conventional mechanism forinserting and removing electronic circuit units;

[0033]FIG. 2 is an exploded perspective view of a lever 12 in FIG. 1 forinserting and removing;

[0034]FIG. 3 is a view for explaining an insertion of the electroniccircuit unit 10 shown in FIG. 1 to the shelf 20 and a lock operation;

[0035]FIG. 4 is a view of an exterior of a communication apparatus 5,where electronic circuit units 1 having levers 30 for inserting andremoving according to the present invention are mounted;

[0036]FIG. 5 is a view of an exterior of the electronic circuit unit 1wherein the levers 30 for inserting and removing according to thepresent invention are provided at upper and lower parts of theelectronic circuit unit 1;

[0037]FIG. 6 is a view of an exterior showing a state where theelectronic circuit unit 1 is mounted to a shelf 100;

[0038]FIG. 7 is a view showing a state where a guide pin 70 is insertedinto a guide hole forming part 110 according to the present invention;

[0039]FIG. 8 is an exploded perspective view of the lever 30 forinserting and removing, the cover part 32 and others, provided at thelower part of the electronic circuit unit 1, shown and seen from a Y1side to a Y2 side in FIG. 5-(A);

[0040]FIG. 9 is an exploded perspective view of the lever 30 forinserting and removing, the housing part 31 and others, provided at thelower part of the electronic circuit unit 1, shown and seen from a Y1side to a Y2 side in FIG. 5-(B);

[0041]FIG. 10 is a cross-sectional view taken on the plane A-A of FIG.5-(A) with regard to the housing part 31, the cover part 32, the lever30, the electronic circuit board 60 and others that are provided to thesurface board 50 provided at the lower part of the electronic circuitunit 1;

[0042]FIG. 11 is a view of an exterior of a modified example of theelectronic circuit unit 1 wherein the levers 30 for inserting andremoving are provided at upper and lower parts of the electronic circuitunit 1;

[0043]FIG. 12 is a view showing a state prior to where the electroniccircuit unit 1 is inserted to the shelf 100;

[0044]FIG. 13 is a view showing a state where the electronic circuitunit 1 starts being inserted to the shelf 100;

[0045]FIG. 14 is a view showing a state where the electronic circuitunit 1 is further inserted to the shelf 100;

[0046]FIG. 15 is a view showing a state where the lever 30 is rotatedcounterclockwise, so that the engagement of the groove forming part 80-4and the projection part 32-1 is off simultaneously;

[0047]FIG. 16 is a view showing a state where the electronic circuitunit 1 is further inserted to the shelf 100 by leverage, following thestate shown in FIG. 15;

[0048]FIG. 17 is a view showing a principle wherein the engaging part80-2 of the stopper 80 is slid on the insertion guide surface 31-3 inthe state shown in FIG. 16;

[0049]FIG. 18 is a view showing a state where the engaging part 80-2 ofthe stopper 80 is further slid on the insertion guide surface 31-3beneath from a state shown in FIGS. 16 and 17, so that the outsidesurface 80-6 of the engaging part 80-2 of the stopper 80 is positionedat an acute angle to part 200 that is a lower end part of the insertionguide surface 31-3;

[0050]FIG. 19 is a view showing a state where outside surface 80-6 ofthe engaging part 80-2 of the stopper 80 passes through the acute anglepart 200 that is a lower end part of the insertion guide surface 31-3,so that the inside surface 80-5 of the engaging part 80-2 of the stopper80 comes in contact with the engaging surface 31-2;

[0051]FIG. 20 is a view showing a state as a result of the lever 30being rotated clockwise or a force (in the direction of the arrow A inFIG. 20) pulling out the electronic circuit unit 1 by vibration or thelike being applied to the electronic circuit unit 1 in a state shown inFIG. 19;

[0052]FIG. 21 is a view showing a state where the lever 30 is furtherrotated counterclockwise from the state shown in FIG. 19 so that theelectronic circuit unit 1 is inserted;

[0053]FIG. 22 is a view showing a state as a result of the lever 30being rotated clockwise or a force (in the direction of the arrow A inFIG. 20) pulling out the electronic circuit unit 1 by vibration or thelike being applied to the electronic circuit unit 1 in a state shown inFIG. 21;

[0054]FIG. 23 is a view showing a principle in the state shown in FIG.22;

[0055]FIG. 24 is a view showing a state where the electronic circuitunit 1 is further inserted, following the state shown in FIG. 21, byrotating the lever 30 counterclockwise;

[0056]FIG. 25 is a view consecutively showing the lever 30 and thestopper 80 as shown in FIGS. 19, 21, and 24;

[0057]FIG. 26 is a view showing a state where the lever 30 is furtherrotated counterclockwise from the state shown in FIG. 24;

[0058]FIG. 27 is a view showing that the engagement of the insidesurface 80-5 of the engaging part 80-2 of the stopper 80 with theengaging surface 31-2 is off (no longer engaging) from the state shownin FIG. 26;

[0059]FIG. 28 is a view showing a state where the stopper 80 is furtherrotated counterclockwise from a state shown in FIG. 27;

[0060]FIG. 29 is a view showing a principle of the state shown in FIG.28;

[0061]FIG. 30 is a view showing a final state with regard to lifting ofthe lock of the lever 30;

[0062]FIG. 31 is a view showing a state where the operation part 30-5 ofthe lever 30 is rotated clockwise from the state shown in FIG. 30;

[0063]FIG. 32 is a view showing a state where the operation part 30-5 ofthe lever 30 is further rotated clockwise from the state shown in FIG.31 so that the outside of the projection part 109 of the front frame 106comes in contact with the claw part 30-2 of the lever 30 as shown by thearrow A; and

[0064]FIG. 33 is a view showing a state where the electrical circuitunit 1 is pulled from the shelf 100 by using the leverage.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0065] A description will now be given, with reference to FIGS. 4through 33, of embodiments of the present invention.

[0066]FIG. 4 is a view of an exterior of a communication apparatus 5,where electronic circuit units 1 having levers 30 for inserting andremoving according to the present invention are mounted. Referring toFIG. 4, a large number of the electronic circuit units 1 are mounted tothe communication apparatus 5 by operating the levers 30.

[0067]FIG. 5 is a view of an exterior of the electronic circuit unit 1wherein the levers 30 for inserting and removing according to thepresent invention are provided at upper and lower parts of theelectronic circuit unit 1. More particularly, FIG. 5-(A) is aperspective view of the electronic circuit unit 1 seen from the side ofa connector part 40, and FIG. 5-(B) is a perspective view of theelectronic circuit unit 1 seen from the side of the levers 30.

[0068] Referring to FIG. 5, the electronic circuit unit 1 consists of anelectronic circuit board 60, the connector part 40 provided at an endpart of the electronic circuit board 60, surface boards 50 provided atupper and lower parts of the other end part of the electronic circuitboard 60 situated at opposite sides to the connector part 40, two of thelevers 30 provided at the respective surface boards 50, and others.

[0069] The respective levers 30 are sandwiched between housing parts 31and cover parts 32, and provided at the upper and lower parts of thesurface board 50. The housing part 31 and the cover part 32 may becalled a housing member that houses the lever 30 and others. It is notalways necessary to provide the levers 30 to both the upper and lowerparts of the surface board 50. The lever 30 may be provided at only theupper or lower part of the surface board 50. The levers 30 provided tothe upper and lower parts of the surface boards 50 have the samestructures except for a pin 31-6 described later and shown in FIG. 9.

[0070] A guide rail 41 is provided at a lower part of the electroniccircuit unit 1, so that the electronic circuit unit 1 can be slid on aguide part 101 (shown in FIG. 6 and described later) of the shelf 100 ofthe communication apparatus 5 wherein the electronic circuit unit 1 ismounted.

[0071] Hatched parts of the surface board 50, the housing part 31, andthe cover part 32 shown in FIG. 5, are surfaces that contact with ashield gasket 105 (described later and shown in FIG. 6) of the shelf 100or another neighboring electronic circuit unit.

[0072] As shown in FIG. 5, the shield gasket 105 shown in FIG. 6 comesin contact with not only the surface board 50 but also rear end parts ofthe housing part 31 and the cover part 32. In addition, a shield gasket35 is provided to a side of the surface board 50 opposite to the sidewhere the lever 30 is positioned. Because of the above mentionedstructure, the housing part 31 and the cover part 32 form a shieldstructure with the surface board 50, so that it is possible to shieldleakage of an electromagnetic wave from the electronic circuit unit 1 tothe outside. Furthermore, because of this structure, in a case where thesurface board 50 is to be made of sheet metal, it is possible to form aconfiguration of the surface board 50 easily. In this case, it ispreferable that the housing part 31 and the cover part 32 are made ofmetal. If the housing part 31 and the cover part 32 are made of resin,it is preferable to implement to cover their surfaces with conductivematerials.

[0073] Next, the shelf 100 provided inside of the communicationapparatus 5, wherein the above described electronic circuit unit 1 ismounted, will be described.

[0074]FIG. 6 is a view of an exterior showing a state where theelectronic circuit unit 1 is mounted to a shelf 100.

[0075] Referring to FIG. 6, the shelf 100 consists of guide boards 102,a side board 104, front frames 106, a back board wiring board 103, andothers. The guide boards 102 are provided at upper and lower parts ofthe shelf 100. The side board 104 is provided between the guide board102 provided at the upper part of the shelf 100 and the guide board 102provided at the lower part of the shelf 100. The front frame 106 isprovided at an end part in an X2 direction of the guide board 102. Theback board wiring board 103 is provided at an end part in an X1direction of the guide board 102.

[0076] A large number of guide parts 101 are provided at the guide board102. The guide rail 41 (shown in FIG. 5) provided at the lower part ofthe electronic circuit unit 1 is situated on the guide part 101, so thatthe electronic circuit unit 1 can be slid. A connector 150 which can beconnected to the connector part 40 of the electronic circuit unit 1 isprovided on the back board wiring board 103.

[0077] The shield gaskets 105 are provided on surfaces of the frontframes 106 facing each other, which front frames 106 are provided at theupper and lower parts of the shelf 100. The shield gaskets 105 come incontact with the surface board 50 and the rear parts of the housing part31 and the cover part 32 so as to form a shield structure with a shieldgasket provided at the side board 104. And thereby, it is possible toshield leakage of an electromagnetic wave from the electronic circuitunit 1 to an outside.

[0078] A guide groove forming part 107 is formed on an upper surface ofthe front frame 106 provided at a lower part of the shelf 100. The guidegroove forming part 107 forms a straight line in an X1-X2 direction withthe guide part 101. Therefore, as well as the guide part 101, the guiderail 41 (shown in FIG. 5) provided at a lower part of the electroniccircuit unit 1 is situated on the guide groove forming part 107, so thatthe electronic circuit unit 1 can be slid.

[0079] A groove forming part 108 is formed in the surface at a side ofthe X2 direction of the front frame 106. A projection part 109 is formedby the groove forming part 108 and the surface at the side of the X2direction of the front frame 106.

[0080] Furthermore, guide hole forming parts 110 for positioning theelectronic circuit unit 1 to the shelf 100 are provided on the surfaceat a side of an X2 direction of the front frame 106. That is, the guidepins 70 provided at vicinities of the levers 30 provided at the upperand lower parts of the electronic circuit unit 1 are inserted into the,guide hole forming parts 110 provided on the surface at the side of anX2 direction of the front frame 106 provided at upper and lower parts ofthe electronic circuit unit 1. Because of this, the electronic circuitunit 1 is positioned to the shelf 100.

[0081] Here, a structure of the guide pin 70 will be described withreference to FIG. 7. FIG. 7 is a view showing a state where the guidepin 70 is inserted into the guide hole forming part 110. Moreparticularly, FIG. 7-(A) is a cross-sectional view taken on the X-Yplane in FIG. 6, FIG. 7-(B) is a cross-sectional view taken on the X-Zplane in FIG. 6, and FIG. 7-(C) is a cross-sectional view taken on theY-Z plane in FIG. 6.

[0082] Referring to FIG. 7-(B), the guide pin 70 consists of apositioning part 70-1 and a guide part 70-2.

[0083] Referring to FIG. 7-(C), the width in the Y1-Y2 directions of theguide pin 70 shown in FIG. 6 is shorter than a diameter 2 a of the guidehole forming part 110 by a length y in the cross section of the Y-Zsurface of the positioning part 70-1. The guide pin 70 is positionedagainst the guide hole forming part 110 in right and left directions(the Y1-Y2 direction) by the positioning part 70-1. Because of this,even if the surface board 50 is pushed by the elastic force of theshield gasket between the neighboring electronic circuit units, theguide pin 70 can be inserted into the guide hole forming part 110securely.

[0084] For example, assuming that the guide pin 70 does not have theabove mentioned structure, in a case where a plurality of the electroniccircuit units 1 are mounted to the shelf 100, if one of the electroniccircuit units 1 is mounted to a center of the shelf 100 last, thesurface boards of the right and left electronic circuit units are pushedto the sides, where the electronic circuit unit is not mounted, by theelastic force of the shield gasket. Therefore, in this case, the widthof a part of the shelf 100, where the center electronic circuit unit isinserted, is too narrow to insert the center electronic circuit unit.However, according to the structure-of the guide pin 70 of the presentinvention, it is possible to prevent the above mentioned problem.

[0085] Furthermore, a gap is provided in upper and lower directions ofthe guide hole forming part 110 (Z1-Z2 directions) so as to cancel aproblem of measurement error between the guide hole forming part 110positioned at the upper part of the shelf 100 and the guide hole formingpart 110 positioned at the lower part of the shelf 100. The measurementerror between the guide hole forming parts 110 positioned at the upperand lower parts of the shelf 100 is caused by an accumulation ofdimensional tolerance of a large number of parts forming the shelf 100.Similarly, an measurement error between the guide pin 70 positioned atthe upper and lower parts of the electronic circuit unit 1 is caused byan accumulation of dimensional tolerance of a large number of partsforming the electronic circuit unit 1. Hence, the gap is provided basedon a difference between the dimensional tolerances of the guide holeforming parts 110 and the guide pins 70.

[0086] More particularly, as shown in FIG. 7-(C), the positioning part70-1 of the guide pin 70 has a cross section wherein an arc of anexternal circumference is made wherein the center is shifted from thecenter of an external circumference of the guide hole forming part 110by a distance b, and the radius is the same as the radius of an externalcircumference of the guide hole forming part 110 or smaller than theexternal circumference of the guide hole forming part 110 by x.

[0087] Accordingly, the movable distance in upper and lower directions(Z1-Z2 direction) in the guide hole forming part 110, is always constantat any point of the external circumference of the positioning part 70-1of the guide pin 70. That is, the movable distance is a length b in theupper and lower directions (Z1-Z2 direction). Therefore, the electroniccircuit unit 1 can be moved in the upper and lower directions (Z1-Z2direction) against the shelf 100. Because of this, the measurementerrors of the distance between the guide hole forming parts 110positioned at the upper and lower parts of the shelf 100 and themeasurement errors of the distance between the guide pins 70 positionedat the upper and lower parts of the electronic circuit unit 1, can benegated.

[0088] The guide part 70-2 has a head end part having a taperingconfiguration. Because of this, the guide pin 70 can be guided into theguide hole forming part 110 by the guide part 70-2.

[0089] Since the guide pin 70 has the above mentioned configuration, itis not necessary to make the guide hole having a cross section of anellipse that is difficult to be formed. Rather, it is possible to easilymake the guide hole forming part 110 having a cross section of a circlethat is easy to be formed, so that the shelf 100 can be made easily.

[0090] Next, structure of the lever 30, and the housing part 31 and thecover part 32 that sandwich the lever 30, will be described.

[0091]FIG. 8 is an exploded perspective view of the lever 30 forinserting and removing, the cover part 32 and others, provided at thelower part of the electronic circuit unit 1, shown and seen from a Y1side to a Y2 side in FIG. 5-(A). FIG. 9 is an exploded perspective viewof the lever 30 for inserting and removing, the housing part 31 andothers, provided at the lower part of the electronic circuit unit 1,shown and seen from a Y1 side to a Y2 side in FIG. 5-(B). Accordingly,the lever 30 for inserting and removing, the housing part 31 and thecover part 32 shown in FIGS. 8 and 9 are provided at the lower part ofthe electronic circuit unit 1.

[0092] Referring to FIGS. 8 and 9, the lever 30 for inserting andremoving consists of a fixing part 30-1, a claw part 30-2, an operationpart 30-5, an arm part 30-6, and others.

[0093] The fixing part 30-1 comes in contact with an inside part of theprojection part 109 (shown in FIG. 6) of the front frame 106 of theshelf 100, when the electronic circuit unit 1 is inserted into the shelf100, and then the electronic circuit unit 1 is fixed by the fixing part30-1.

[0094] The claw part 30-2 comes in contact with an outside part of theprojection part 109 of the shelf 100 when the electronic circuit unit 1is pulled from the shelf 100. The electronic circuit unit 1 can bepulled from the shelf 100 by applying the leverage wherein the contactposition is a fulcrum.

[0095] The operation part 30-5 for operating the arm part 30-6 isprovided at an end part of the lever 30 for inserting and removing. Arotation center part 30-3 is provided at an opposite side to the sidewhere the operation part 30-5 is situated. Therefore, an operator canoperate the operation part 30-5 manually, and thereby the arm part 30-6can rotate in a state where the rotation center part 30-3 is the centerof the rotation of the arm part 30-6.

[0096] A rotation center part 30-4 of a stopper 80 described below isprovided right over the rotation center part 30-3 of the arm part 30-6.Furthermore, a side surface of the stopper 80 forms the same surface asa side surface of the lever 30 for inserting and removing. A grooveforming part 30-7 is formed on the side surface of the lever 30 forinserting and removing so as to rotate the stopper 80.

[0097] Next, the stopper 80 will be described.

[0098] A rotation center part 80-1 is provided at a designated part ofthe arm part 80-3 of the stopper 80. A spring 55 is housed in therotation center part 80-1. The stopper 80 is provided to the lever 30for inserting and removing, so that the rotation center part 80-1coincides with the rotation center part 30-4 of the stopper 80 providedin the lever 30 for inserting and removing. A force is applied in arotating direction of the spring 55. Therefore, the lever 30 forinserting and removing and the stopper 80 can be rotated by the spring55. Although the spring 55 is used in this specification as anembodiment of the present invention, other kinds of elastic bodies maybe used having the same function as the spring 55.

[0099] An engaging part 80-2 projects from the end part of the arm part80-3 to the sides of the housing part 31 and the cover part 32 so as toextend like a projection. The engaging part 80-2 has an inside surface80-5 that is a surface at a side of the rotation center part 80-1 and anoutside surface 80-6 that is an opposite side surface to the insidesurface 80-5.

[0100] A groove forming part 80-4 is formed at an opposite side to theengaging part 80-2 from a position of the rotation center part 80-1 ofthe arm part 80-3. The stopper 80 is fixed by meshing the groove formingpart 80-4 with a projection part 32-1 (described later) of the coverpart 32.

[0101] Next, the housing part 31 and the cover part 32 that sandwich thelever 30 for inserting and removing and the stopper 80 will beexplained.

[0102] Referring to FIG. 8, the housing part 31 has a plate structure. Alower level part 31-8 is formed so that the stopper 80 can rotate on thehousing part 31. At a lower part of the lower level part 31-8, arotation axis 31-1 for allowing the lever 30 to be rotated extends fromthe lower level part 31-8 to the side of the lever 30. Therefore, therotation center part 30-3 of the lever 30 is provided at the rotationaxis 31-1. Furthermore, a rotation stopping part 31-5 for stopping therotation of the lever 30, that contacts with the arm part 30-6 of thelever 30, is formed at a upper part of the housing part 31.

[0103] An insertion guide surface 31-3 and an engaging surface 31-2 areprovided at a vicinity of the rotation stopping part 31-5 of the lever30. The outside surface 80-6 of the engaging part 80-2 of the stopper 80is guided by the insertion guide surface 31-3 when the electroniccircuit unit 1 is inserted to the shelf 100. The engaging surface 31-2engages with the inside surface 80-5 of the engaging part 80-2 of thestopper 80. The engaging surface 31-2 and the insertion guide surface31-3 form an acute angle part 200.

[0104] In addition, an engaging lifting guide surface 31-4 is providedat the back of the engaging surface 31-2. When the electronic circuitunit 1 is pulled out, the engagement of the inside surface 80-5 of theengaging part 80-2 of the stopper 80 is lifted. The outside surface 80-6of the engaging part 80-2 of the stopper 80 is guided by the engaginglifting guide surface 31-4 until the operator pulls the lever 30forward.

[0105] As shown in FIG. 9, pins 31-6 extend from a surface outside ofthe housing 31. The housing part 31 sandwiching the lever 30 and otherswith the cover part 32 can be provided to the surface board 50 by thepins 31-6. As described above, FIGS. 8 and 9 show a case where the lever30 is provided at the lower part of the electronic circuit unit 1.However, in a case where the lever 30 is provided at the upper part ofthe electronic circuit unit 1, the pins 31-6 are not provided on thesurface of outside of the housing 31, but pins extend from a surfaceoutside of the cover part 32 so that the cover part 32 can be providedto the surface board 50.

[0106] Referring to FIG. 9, the cover part 32 has a substantially samestructure as the housing part 31. However, the projection part 32-1,projecting to an inside (a side of the lever 30) of the cover part 32,is provided at a lower side of the surface of the inside (the side ofthe lever 30) of the cover part 32. The projection part 32-1 has twofunctions. One is to guide the outside surface 80-6 of the engaging part80-2 of the stopper 80 to the insertion guide surface 31-3 of thehousing part 31. The other is to engage the groove forming part 80-4 ofthe stopper 80 in a state where the lever 30 is rotated counterclockwiseso that the stopper can be fixed.

[0107]FIG. 10 is a cross-sectional view taken on the plane A-A of FIG.5-(A) with regard to the housing part 31, the cover part 32, and thelever 30, the electronic circuit board 60 and others that are providedto the surface board 50 provided at the lower part of the electroniccircuit unit 1.

[0108] Referring to FIG. 10, a positioning hole forming part 60-1 isprovided on the electronic circuit board 60 shown in FIG. 5. A piercinghole forming part 50-1 where the pin 31-6 of the housing part 31 piercesis provided on the surface board 50. Under the above mentionedstructure, the pin 31-6 pierces into the surface board 50 and theelectronic circuit board 60 through the piercing hole forming part 50-1and the positioning hole forming part 60-1. Therefore, it is possible toassemble the electronic circuit board 60 and the lever 30 after thepositioning relationship of the electronic circuit board 60 and thelever 30 is determined securely. Furthermore, it is possible to make themeasurement error between the connector part 40 and the fixing part 30-1of the lever 30 small.

[0109] In the meantime, the present invention is not limited to theembodiment shown in FIG. 5. Rather, the present invention may be appliedto an embodiment shown in FIG. 11. That is, FIG. 11 is a view of anexterior of a modified example of the electronic circuit unit 1 whereinthe levers 30 for inserting and removing are provided at upper and lowerparts of the electronic circuit unit 1.

[0110] Referring to FIG. 11, in this modified example, the surface board50 of the electronic circuit unit 1 and the housing part 31 of the lever30 are formed in a body, and thereby it is possible to make the width inY1-Y2 direction of the electronic circuit unit 1 short. Furthermore, itis possible to reduced the number of parts forming the electroniccircuit unit 1 so that it is possible to contribute to reducemanufacturing costs of the electronic circuit unit 1. In addition, it ispossible to make the surface board 50 easily by die casting.

[0111] Next, a mechanism for inserting and removing electronic circuitunit 1 having the above mentioned structure will be described.

[0112] FIGS. 12-32 show a mechanism of the lever 30 provided at thelower part of the electronic circuit unit 1. The lever 30 inserts intoand moves against the front frame 106. Since the lever 30 provided atthe upper part has substantially same mechanism, explanation thereofwill-be omitted.

[0113]FIG. 12 is a view showing a state prior to where the electroniccircuit unit 1 is inserted to the shelf 100. The spring 55 and thestopper 80 rotated by the spring 55 are provided at the lever 30. Oneend of the spring 55 is connected to the rotation center part 30-3 ofthe arm part 30-6 of the lever 30. The lever 30 is rotated clockwise.The stopper 80 receives a force to be rotated clockwise by a force ofthe spring 55. The groove forming part 80-4 of the stopper 80 engageswith the projection part 32-1 of the cover part 32, so that the stopper80 is fixed. If the cover part 32 does not have the projection part32-1, the stopper 80 is rotated clockwise and the lever 30 is rotatedcounterclockwise by the force of the spring 55. However, the projectionpart 32-1 is provided at the housing part 32 in the present invention.Accordingly, the stopper 80 is fixed by engaging the groove forming part80-4 and the projection part 32-1.

[0114]FIG. 13 is a view showing a state where the electronic circuitunit 1 starts being inserted to the shelf 100. The claw part 30-2 of thelever 30 comes in contact with a front surface of the projection part109 of the front frame 106.

[0115]FIG. 14 is a view showing a state where the electronic circuitunit 1 is further inserted to the shelf 100. In this state, the lever 30does not move because of an engagement of the groove forming part 80-4and the projection part 32-1. However, since more forces is applied froman arrow A direction to the claw part 30-2 of the lever 30 comingcontact with the front surface of the projection part 109 of the frontframe 106, the lever 30 is rotated a little and counterclockwise, sothat the engagement of the groove forming part 80-4 and the projectionpart 32-1 is off, as shown in FIG. 15.

[0116] As shown in FIG. 15, based on that the engagement of the grooveforming part 80-4 and the projection part 32-1 being off, the lever 30is rotated counterclockwise some amount by the force of the spring 55.On the other hand, a force rotating the stopper 80 clockwise by thespring 55 is applied to the stopper 80. Because of this, after theengagement of the groove forming part 80-4 and the projection part 32-1is off, the stopper 80 slides on the projection part 32-1, and therebythe engaging part 80-2 of the stopper 80 moves in the direction of theinsertion guide surface 31-3. However, since the stopper 80 comes incontact with the projection part 32-1, the stopper 80 cannot move at allafter the outside surface 80-6 of the engaging part 80-2 of the stopper80 comes in contact with a highest end (shown by the arrow A in FIG. 15)of the insertion guide surface 31-3 of the housing part 31.

[0117] If the projection part is not provided at the housing part 32,the outside surface 80-6 of the engaging part 80-2 of the stopper 80comes in contact with a surface situated at a side further right thanthe highest end (shown by the arrow A in FIG. 15) of the insertion guidesurface 31-3. Here, the highest end is situated at a limiting positionwhere the stopper 80 can be guided by the insertion guide surface 31-3.As a result of this, the stopper 80 cannot be slid even if the operatoroperates the stopper. However, the outside surface 80-6 of the engagingpart 80-2 of the stopper 80 is stopped moving at the highest end of theinsertion guide surface 31-3 by the projection part 32-1, so that theabove mentioned problem can be avoided. That is, the projection part32-1 is positioned so that the outside surface 80-6 of the engaging part80-2 of the stopper 80 is stopped at the highest end of the insertionguide surface 31-3.

[0118] In a state shown in FIG. 15, the fixing part 30-1 of the lever 30is situated in the groove forming part 108 located at an inside of theprojection part 109 of the front frame 106. Furthermore, the operatorcan easily see by rotating the operation part 30-5 of the lever 30 withan operator's finger that lock operation is ready to start, based on thelever 30 being rotated counterclockwise some amount by the force of thespring 55.

[0119]FIG. 16 is a view showing a state where the electronic circuitunit 1 is further inserted to the shelf 100 by leverage from the stateshown in FIG. 15. The fixing part 30-1 of the lever 30 comes in contactwith the inside of the projection part 109 of the front frame 106. Theoutside surface 80-6 of the engaging part 80-2 of the stopper 80 is slidon the insertion guide surface 31-3. Here, the outside surface 80-6 ofthe engaging part 80-2 of the stopper 80 is coated with a lubricatingmaterial, Teflon (registered trade mark) coating, or the like, so thatthe outside surface 80-6 is easy to slide.

[0120]FIG. 17 is a view showing a principle wherein the engaging part80-2 of the stopper 80 is slid on the insertion guide surface 31-3 inthe state shown in FIG. 16. Referring to FIG. 17, the lever 30 isrotated counterclockwise as shown by a dotted arrow A in FIG. 16. Aforce F is generated in the direction of a line tangential to therotation of the rotation center part 80-1 of the stopper 80. The force Fcan be resolved into a force F1 and a force F2.

[0121] The force F1 is a force in the direction of a point where theengaging part 80-2 of the stopper 80 comes in contact with the insertionguide surface 31-3. The force F1 is applied to the insertion guidesurface 31-3. A reaction force of the spring 55 occurs by operating thelever 30 manually so as to rotate the lever 30 counterclockwise. Theforce F1 occurs based on the reaction force of the spring 55 so that theinsertion guide surface 31-3 is pushed by the stopper 80. As shown inFIG. 17, the force F1 is resolved into a force F3 and a force F4.

[0122] The force F3 is a force in a direction of a tangential line at aposition of the insertion guide surface 31-3 that is a curved surfacewhere the outside surface 80-6 of the engaging part 80-2 of the stopper80 comes in contact. That is, the force F3 is expressed as F3=F1×sinθ_(a). The force F4 is a force in a right-angled direction against thetangential line at a position of the insertion guide surface 31-3 thatis a curved surface where the outside surface 80-6 of the engaging part80-2 of the stopper 80 comes in contact. That is, the force F4 isexpressed as F4=F1×cos θ_(a). In this case, in a case of F3>F4×μ₀+F_(b),the outside surface 80-6 of the engaging part 80-2 of the stopper 80slides on the insertion guide surface 31-3, wherein a frictioncoefficient of the insertion guide surface 31-3 where the outsidesurface 80-6 of the engaging part 80-2 of the stopper 80 comes incontact is defined as μ₀ and the force generated at the insertion guidesurface 31-3 by the spring 55 is defined as F_(b).

[0123] Under the above mentioned principle, the outside surface 80-6 ofthe engaging part 80-2 of the stopper 80 and the insertion guide surface31-3 are set as having a slidable angle θ_(a), more than 20 degrees, forexample. Thus, the engaging part 80-2 of the stopper 80 is slid on theinsertion guide surface 31-3 while pushing against the insertion guidesurface 31-3.

[0124]FIG. 18 is a view showing a state where the engaging part 80-2 ofthe stopper 80 is further slid on the insertion guide surface 31-3 froma state shown in FIGS. 16 and 17, so that the outside surface 80-6 ofthe engaging part 80-2 of the stopper 80 is positioned at the acuteangle part 200 that is a lower end part of the insertion guide surface31-3.

[0125]FIG. 19 is a view showing a state where outside surface 80-6 ofthe engaging part 80-2 of the stopper 80 passes by the acute angle part200 that is a lower end part of the insertion guide surface 31-3, sothat the inside surface 80-5 of the engaging part 80-2 of the stopper 80comes in contact with the engaging surface 31-2. The stopper 80 movessome amount from a state shown in FIG. 18 to a state shown in FIG. 19due to the force of the spring 55.

[0126]FIG. 20 is a view showing a state result of the lever 30 beingrotated clockwise or a force (in the direction of the arrow A in FIG.20) pulling out the electronic circuit unit 1 by vibration or the likebeing applied to the electronic circuit unit 1 in the state shown inFIG. 19.

[0127] In a case where a force pulling out the electronic circuit unit 1by vibration or the like is applied to the electronic circuit unit 1, aforce in a direction of the arrow B is applied from an inside of theprojection part 109 of the front frame 106 to the fixing part 30-1 ofthe lever 30. In this case, the lever 30 is rotated clockwise, so thatthe inside surface 80-5 of the engaging part 80-2 of the stopper 80 ispulled in a direction toward the rotation center part 80-1 of thestopper 80. However, the inside surface 80-5 of the engaging part 80-2of the stopper 80 and the engaging surface 31-2 has an unslidable angleθ_(b) described later. Hence, the engaging part 80-2 of the stopper 80does not slide.

[0128]FIG. 21 is a view showing a state where the lever 30 is furtherrotated counterclockwise from a state shown in FIG. 19 so that theelectronic circuit unit 1 is inserted. Although the stopper 80 isrotated clockwise by the force of the spring 55, the stopper 80 islocked at a position where an orbit of the engaging part 80-2 of thestopper 80 and the engaging surface 31-2 cross.

[0129]FIG. 22 is a view showing a state result of the lever 30 beingrotated clockwise or a force (in the direction of the arrow A in FIG.20) pulling out the electronic circuit unit 1 by the vibration or thelike being applied to the electronic circuit unit 1 in the state shownin FIG. 21. In this case, as well as the state shown in FIG. 20, theinside surface 80-5 of the engaging part 80-2 of the stopper 80 and theengaging surface 31-2 have an unslidable angle θ_(c). Hence, the insidesurface 80-5 of the engaging part 80-2 of the stopper 80 does not slide.

[0130]FIG. 23 is a view showing a principle in the state shown in FIG.22. Referring to FIG. 23, the lever 30 is rotated counterclockwise asshown by a dotted arrow A in FIG. 23. A force F′ occurs in the directionof a tangential line of a rotation of the rotation center part 80-1 ofthe stopper 80. The force F′ can be resolved into a force F5 and a forceF6.

[0131] The force F5 is a force in the direction from a point where theengaging part 80-2 of the stopper 80 comes in contact with the insertionguide surface 31-2 to the rotation center part 80-1. Based on the forceto pull out the electronic circuit unit 1, the force F5 of the engagingpart 80-2 of the stopper 80 is applied to the insertion guide surface31-2. As shown in FIG. 23, the force F5 is resolved into a force F7 anda force F8.

[0132] The force F7 is a force in a direction of a tangential line at aposition of the engaging surface 31-2 that is a curved surface where theinside surface 80-5 of the engaging part 80-2 of the stopper 80 comes incontact. That is, the force F7 is expressed as F7=F5×sin θ_(c). Theforce F8 is a force in a right-angled direction against the tangentialline at a position of the engaging surface 31-2 that is a curved surfacewhere the engaging part 80-2 of the stopper 80 comes in contact. Thatis, the force F8 is expressed as F8=F5×cos θ_(c). In this case, in acase of F7<F8×μ₀+F_(b), the inside surface 80-5 of the engaging part80-2 of the stopper 80 does not slide on the engaging surface 31-2,wherein the friction coefficient of the engaging surface 31-2 where theinside surface 80-5 of the engaging part 80-2 of the stopper 80 comes incontact is defined as μ₀ and the force generated at the engaging surface31-2 by the spring 55 is defined as F_(b).

[0133] Based on the above mentioned principle, the head end of thestopper 80 and the guide surface 31-2 for lock are set as having anunslidable angle θ_(c). This is same as the unslidable angle θ_(b).

[0134]FIG. 24 is a view showing a state where the electronic circuitunit 1 is further inserted from the state shown in FIG. 21 by rotatingthe lever 30 counterclockwise.

[0135] In this state, the stopper 80 comes in contact with the upperpart of the claw part 30-2 that is shown by an arrow A in FIG. 24, sothat the stopper 80 cannot be further rotated against the lever 30clockwise. This is because, even if the lever 30 is further rotatedcounterclockwise, the inside surface 80-5 of the engaging part 80-2 ofthe stopper is locked at a position where the orbit of the insidesurface 80-5 of the engaging part 80-2 of the stopper 80 and theengaging surface 31-2 cross, so that the stopper 80 cannot be furtherrotated against the lever 30 clockwise.

[0136] In this case, in a case where a force is applied so that thelever 30 is rotated clockwise or a force pulling out the electroniccircuit unit 1 by vibration or the like is applied to the electroniccircuit unit 1 in the state shown in FIG. 24, the inside surface 80-5 ofthe engaging part 80-2 of the stopper 80 and the engaging surface 31-2have an unslidable angle θ_(d). Hence, the engaging part 80-2 of thestopper 80 does not slide.

[0137] Thus, the electronic circuit unit 1 is inserted and fixed, asshown in FIGS. 19 through 24, by rotating the lever 30 counterclockwise.During states shown in FIGS. 19-24, the inside surface 80-5 of theengaging part 80-2 of the stopper 80 and the engaging surface 31-2 comein contact with each other consecutively. Therefore, even if theengaging part 80-2 of the stopper 80 is pulled in an axial direction ofthe stopper 80, the inside surface 80-5 of the engaging part 80-2 of thestopper 80 and the engaging surface 31-2 have unslidable angles (θ_(b),θ_(c), θ_(d)) and are fixed.

[0138]FIG. 25 is-a view consecutively showing the lever 30 and thestopper 80 shown in FIGS. 19, 21, and 24.

[0139] Referring to-FIG. 25, the stopper 80 comes in contact and isfixed at the position where the orbit of the engaging part 80-2 of thestopper 80 shown in FIG. 19 crosses with the engaging surface 31-2. Thelever 30 is further rotated counterclockwise so that the stopper 80 isalso rotated counterclockwise wherein the rotation center part 30-3 ofthe lever 30 is a center of the rotation. And thereby, a gap is formedbetween the engaging part 80-2 of the stopper 80 and the engagingsurface 31-2. However, the stopper 80 is rotated clockwise by the forceof the spring 55 so that the stopper 80 continues coming contact withthe engaging surface 31-2. The above mentioned movement of the stopper80 is consecutive in FIGS. 19, 21 and 24.

[0140] According to the engaging surface 31-2 having the above mentionedstructure, a lock mechanism not having play between the lever 30 and thefront frame 106 can be achieved. That is, even if the fixing part 30-1of the lever 30 is in the groove forming part 108 of the front frame 106so that the lever 30 and the front frame 106 are locked, the lever 30does not have play. Therefore, it is possible to secure the connectionbetween the connector part 40 of the electronic circuit unit 1 and theconnector 150 of the back board wiring board 103.

[0141]FIG. 26 is a view showing a state where the lever 30 is furtherrotated counterclockwise from a state shown in FIG. 24. In this case,the arm part 30-6 of the lever 30 comes in contact with the rotationstopping part 31-5 as shown by the arrow A in FIG. 26. Therefore, theleverage applied to the lever 30 does not cause further rotation.Because of this, damaging force on the connection between the connectorpart 40 of the electronic circuit unit 1 and the connector 150 of theback board wiring board 103 is prevented. Here, during the states shownin FIGS. 24 through 26, the inside surface 80-5 of the engaging part80-2 of the stopper 80 and the engaging surface 31-2 have a gap shown byan arrow B in FIG. 26.

[0142] Actions of the electronic circuit unit 1 being pulled out fromthe shelf 100 are shown in FIGS. 27 through 33.

[0143]FIG. 27 is a view showing that the engagement of the insidesurface 80-5 of the engaging part 80-2 of the stopper 80 with theengaging surface 31-2 is off from the state shown in FIG. 26. That is,the stopper 80 is rotated counterclockwise from the state shown in FIG.26, in a state shown in FIG. 27. As shown in FIG. 26, the gap is formedbetween the engaging part of the stopper 80 and the engaging part 31-2.Accordingly, it is possible to rotate the stopper 80 with a light forceeasily. The stopper 80 is rotated counterclockwise, so that the outsidesurface of the engaging part 80-2 of the stopper 80 comes in contactwith the engaging lifting guide surface 31-4.

[0144]FIG. 28 is a view showing a state where the stopper 80 is furtherrotated counterclockwise from the state shown in FIG. 27. The outsidesurface 80-6 of the engaging part 80-2 of the stopper 80 moves on theengaging lifting guide surface 31-4. On the other hand, the lever 30 isrotated clockwise by the force of the spring 55 wherein the rotationcenter part 30-3 is the center of the rotation of the lever 30.

[0145]FIG. 29 is a view showing a principle in the state shown in FIG.28. Referring to FIG. 29, the stopper 80 is rotated in a direction shownby the dotted arrow A (counterclockwise), so that the force F occurs ina direction of the tangential line of the direction of the rotation ofthe engaging part 80-2 of the stopper 80. The force F can be resolvedinto a force F9 and a force F10.

[0146] The force F9 F3 is a force in the direction of a tangential lineat a position of the insertion lifting guide surface 31-4 that is acurved surface where the outside surface 80-6 of the engaging part 80-2of the stopper 80 comes in contact. That is, the force F9 is expressedas F9=F×sin θ_(e). The force F10 is a force in a right-angled directionagainst the tangential line at a position of the insertion lifting guidesurface 31-4 that is a curved surface where the outside surface 80-6 ofthe engaging part 80-2 of the stopper 80 comes in contact. That is, theforce F10 is expressed as F10=F×cos θ_(e). In this case, in a case ofF9>F10×μ₀+F_(b), the stopper 80 slides on the insertion lifting guidesurface 31-4, wherein the friction coefficient of the surface where theoutside surface 80-6 of the engaging part 80-2 of the stopper 80 comesin contact is defined as μ₀ and the force generated at the insertionlifting guide surface 31-4 by the spring 55 is defined as F_(b).According to the above mentioned principle, the insertion lifting guidesurface 31-4 is set so as to have the slidable angle θ_(e). The outsidesurface 80-6 of the engaging part 80-2 of the stopper 80 slides on theinsertion lifting guide surface 31-4 while pushing against the insertionlifting guide surface 31-4

[0147]FIG. 30 is a view showing a final stage with regard to lifting ofthe lock of the lever 30 wherein the stopper 80 is further rotated fromthe state shown in FIG. 28. The stopper 80 is further rotatedcounterclockwise from the state shown in FIG. 28 so that the lever 30 isrotated clockwise automatically by the force of the spring 55. In thisstate, the operation part 30-5 of the lever 30 is located nearer to theoperator than the state shown in FIG. 26. Hence, the operator can rotatethe head end of the operation part 30-5 of the lever 30 clockwise withhis finger, without inserting the finger deeply.

[0148] If the lever 30 protrudes from the surface board 50 when theelectronic circuit unit 1 is mounted on the shelf 100, it is difficultto see indication parts, such as a light-emitting diode, provided on thesurface board 50. As shown in FIG. 5, the front surface of the surfaceboard 50 is situated at the same position as a position where the frontsurface of the lever 30 is situated. That is, the surface board 50 andthe front surface of the lever 30 form same surface. However, in a stateshown in FIG. 30, the operation part 30-5 of the lever 30 is locatednearer to the operator than the state shown in FIG. 26. Accordingly, theoperator can operate the lever 30 without inserting the finger deeply.Hence, this mechanism has good operability and is convenient.

[0149]FIG. 31 is a view showing a state where the operation part 30-5 ofthe lever 30 is rotated clockwise from the state shown in FIG. 30.

[0150]FIG. 32 is a view showing a state where the operation part 30-5 ofthe lever 30 is further rotated clockwise from the state shown in FIG.31 so that the outside of the projection part 109 of the front frame 106comes in contact with the claw part 30-2 of the lever 30 as shown by thearrow A.

[0151] From the state shown in FIG. 27 to the state shown in FIG. 32,the guide pin 70 of the lever 30 remains inserted in the guide holeforming part 110 of the front frame 106. Therefore, the electroniccircuit unit 1 does not move. The operator can rotate the lever 30 witha light force.

[0152]FIG. 33 is a view showing a state where the electrical circuitunit 1 is pulled from the shelf 100 by using the leverage.

[0153] Referring to FIG. 33, the operator can rotate the lever 30clockwise by using the leverage, wherein a point (shown by the arrow A)where the claw part 30-2 of the lever 30 comes in contact with theoutside of the projection part 109 of the front frame 106 is a fulcrum.As a result of this, engagement between the guide pin 70 of the lever 30and the guide hole forming part 110 of the front frame 106 is off, sothat the electrical circuit unit 1 can be pulled from the shelf 100.

[0154] Thus, it is possible to securely insert and remove the electroniccircuit unit 1 against the shelf 100 by using the mechanism forinserting and removing of the electronic circuit unit 1.

[0155] The present invention is not limited to these embodiments, butvariations and modifications may be made without departing from thescope of the present invention.

[0156] This patent application is based on Japanese priority patentapplication No. 2002-188324 filed on Jun. 27, 2002, the entire contentsof which are hereby incorporated by reference.

What is claimed is:
 1. A mechanism for inserting and removing electroniccircuit units against a shelf of an electrical device where theelectronic circuit units are installed, wherein the shelf includes agroove forming part, the electrical circuit unit includes a rotatablelever having a head end where a fixing part is provided; a rotatablestopper connected to the lever and having a head end where an engagingpart is provided; and a housing member housing the lever and the stopperwhere an engaging surface engaging with the engaging part of the stopperis provided inside thereof, the electrical circuit unit is locked withthe shelf by rotating the lever so as to engage the groove forming partof the shelf with the engaging part of the stopper, and the engagementbetween the engaging surface of the housing-member and the engaging partof the stopper is not off even if a force to lift the lock is applied tothe electrical circuit unit.
 2. The mechanism for inserting and removingelectronic circuit units, as claimed in claim 1, wherein the engagingsurface of the housing member is a curved surface, the engaging surfaceof the housing member is engaged with the engaging part of the stopperby crossing the engaging surface of the housing member with an orbit ofthe rotation of the engaging part of the stopper, and the engagementbetween the engaging surface of the housing member and the engaging partof the stopper is not off even if a force to lift the lock between theshelf and the electrical circuit unit is applied to the electricalcircuit unit.
 3. The mechanism for inserting and removing electroniccircuit units, as claimed in claim 1, wherein the housing member furtherincludes a rotation stopping part, and the lever cannot be moved, afterthe lever is further rotated so that the lever comes in contact with therotation stopping part.
 4. The mechanism for inserting and removingelectronic circuit units, as claimed in claim 1, wherein the housingmember further includes a housing part having a rotational axis againstwhich the lever is rotated; and a cover part facing to the housing part,and the engaging surface is provided to the housing part and/or thecover part.
 5. The mechanism for inserting and removing electroniccircuit units, as claimed in claim 1, wherein the housing member furtherincludes an engaging lifting guide surface, and the engaging part of thestopper is guided on the engaging lifting guide surface by rotating thestopper and then the lever is rotated, so that the lock between theelectrical circuit unit and the shelf is off.
 6. The mechanism forinserting and removing electronic circuit units, as claimed in claim 1,wherein the stopper is connected to the lever through a spring so thatthe stopper and the lever are rotated by a force of the spring.
 7. Themechanism for inserting and removing electronic circuit units, asclaimed in claim 1, wherein the shelf further includes a guide holehaving a circular configuration, the housing member further includes aguide pin inserting into the guide hole forming part, and the guide pinhas a configuration wherein the guide pin and the guide hole formingpart are positioned in a horizontal direction and the guide pin can bemoved in the guide hole forming part in a longitudinal direction.
 8. Themechanism for inserting and removing electronic circuit units, asclaimed in claim 1, wherein the electrical circuit unit further includesa surface board where the lever is provided, and the housing member andthe surface board are formed in a body.
 9. The mechanism for insertingand removing electronic circuit units, as claimed in claim 8, whereinthe electronic circuit unit further includes an electrical circuit boardwhere a hole forming part for positioning is provided, the housingmember for housing the lever includes a pin, the surface board includesa piercing hole forming part, the pin pierces to the piercing holeforming part of the surface board and the hole forming part forpositioning of the electrical circuit board and thereby the electricalcircuit board and the lever are positioned.
 10. A mechanism forinserting and removing electronic circuit units against a shelf of anelectrical device where the electronic circuit units are installed,wherein the shelf includes a groove forming part, the electrical circuitunit includes a rotatable lever having a head end where a fixing part isprovided; a rotatable stopper connected to the lever and having a headend where an engaging part is provided; and a housing member housing thelever and the stopper where a projection part fixing an insertion guidesurface where the engaging part is guided to the stopper by rotating thelever is provided inside thereof, and if a designated force is appliedto the lever, the lever is rotated and the fixing part of the lever isengaged with the groove forming part of the shelf, and fixing of thestopper by the projection part of the housing member is lifted so thatthe engaging part of the stopper comes in contact with the insertionguide surface.
 11. The mechanism for inserting and removing electroniccircuit units, as claimed in claim 10, wherein the stopper furtherincludes another groove forming part, and the stopper is fixed to theprojection part by engaging the other groove forming part with theprojection part of the housing member.